Perfectly uniform arrows on a map in Tableau

Show me the Way: Putting Directed Arrows on Maps in Tableau

This is the continuation of a blog post I published a few weeks ago on how to draw directed arrows in Tableau. The approach introduced there – I dubbed it the “linear” approach, as instead of drawing one line we created two additional lines for the arrowheads – works fine on scatterplots, but things turn out to be a bit more difficult when working with maps. This article shows how these difficulties can be overcome using some on-the-fly reprojection of our data. While I claim the arrows to be my original idea (at least I didn’t find anything similar on the web – please correct me if I’m wrong!), I can’t and won’t take credit for this one. All original work was done by Alan Eldridge and the @mapsOverlord herself, Tableau’s Sarah Battersby in an article on hexbinning on Alan’s blog back in 2015. Sarah is an absolute expert on all things map projection, as she has shown time and time again in articles on the topic on the official Tableau and Tableau Public blogs and elsewhere (as in: real scientific publications).

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Directed arrows on a Tableau scatterplot

Giving your Flows a Direction in Tableau

In a recent blog post I showed how easy it is to create maps in Tableau showing paths, basically lines connecting two points each: the start and end locations. Those can be departure and arrival airports of certain flight routes, origin and destination of refugee flows, source and sink of money transfers, … the possibilities are endless!

But now imagine a map with a line connecting two locations A and B. Or rather many such lines. What information does this hold for you? What insights can you get out of such a viz? There is one very important element still missing! That is: which direction is this connection? Sure, there are cases where direction doesn’t matter, but thinking of the three aforementioned example use cases, many times it does! So let’s give our connecting paths some directionality. Let’s take simple lines and make them arrows!

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Connecting the Dots – Visualizing Paths in Tableau

I had been planning to write this post for a long time. Not only have I been asked many times how to do this in my daily consulting work, but especially during and after my hands-on training “Stretching the Boundaries with Advanced Mapping” at our Tableau Conference On Tour 2017 in Berlin earlier this year. The question is pretty simple: How can I draw paths in Tableau? Oftentimes these are some kind of movement data, e.g. refugees or flight connections. The way to do this in Tableau is actually very easy – and some of the recently introduced features made it even easier – but it’s imperative to understand how Tableau draws lines and how the data therefore needs to be structured.

The route network visualized in Tableau

The route network visualized in Tableau

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Population Lines - the Tableau Edition

Population Lines – the Tableau Edition

In 2013 Dr. James Cheshire from the Centre for Advanced Spatial Analysis at the University College London created a data visualization that was critically acclaimed back then and saw something of a renaissance a few weeks ago when a modified version by Henrik Lindberg made its way onto the Reddit front page. I had been mesmerized by the viz from the beginning, so when it reappeared in my blog reader I decided I had to try reproducing it in Tableau.

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The last available report per BookID is marked

Reporting Self-Updating Data Using Wildcard Union in Tableau

Imagine you have some kind of system that produces reports on your data – for this example I randomly decided to use bookings for events -, and these reports are published on a regular schedule. Now you want to see two things in your report:

  1. The current status of participants per event – both for past events (i.e. the actual number of participants) and for future events (i.e. the current number of people registered).
  2. An overview of how the number of people registered changed over time.

Also, your source system is publishing these data as .csv files. How can this be done?

Well, very easily using the new wildcard union feature introduced in Tableau Desktop 10.1! Read on to see how this can be done.

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